i'm not sure i buy the idea of skimmers 'breaking in,' unless it relates to buildup of residue on the inner surface of the reaction chamber.
afaik, skimmers work by a principle called "foam fractionation" wherein organic particles are caught up in a surface-tension layer at an air-water interface.. and the skimmers work because the large number of small bubbles have a high interface area.
when the bubbles on the top of the column break, their water (already high in organic content) becomes part of the water in the bubbles below...
thereby increasing the organic content of the water until it's nasty, and hopefully spills over into the cup, if things are tuned properly.
so, where in this process would 'breaking in' have a role? what is there to break in? the pump? the venturi?
the only thing i can think of is that when new, the inner surface of the reaction chamber is clean and perfectly smooth. after even a few hours of operation, there's deposits there.
anyhow, my skimmer is a DAS-BX2, and it replaced a small HOB Sealife Systems (RIO 600 driven) on my 75....
it was pulling gunk (probably a strong bourbon and water
within minutes. in fact, after i clean it, it works just as well as it did before, and does not require a new 'break in' period.
so.... wha'as up with this breakin business?
of course, there's only anecdotal evidence either way.